Flavonoids, a large class of compounds widely existed in the nature, are a class of derivative yellow pigment whose parent nucleus is flavone(2-phenylchromone), characterized in that it is with basic framework of C6-C3-C6. Flavonoids can be divided into dozens of categories, flavones, flavanols, isolavones, flavanones, flavanonols, flavanones, anthocyanidins, chalcones and chromones etc., over 4000 kinds of flavonoids are found at present, mainly existed in the leaves, fruits, roots and skin of plants.
The study on flavonoids has become a hot topic in Chinese and foreign medical profession due to its high pharmaceutical value. As a kind of natural drug with broad development prospect, it has large application foreground in fields like medicine and food. These compounds can be used to prevent and cure cardiovascular and cerebrovascular diseases, such as the decrease of fragility of blood vessels, improvement of permeability of blood vessels, decrease of blood fat and cholesterol, prevention and cure of elderly hypertension, cerebral hemorrhage coronary heart disease angina and pectoris, expansion of coronary artery and promotion of coronary blood flow. Many flavone components have the activity of antitussive, anti-inflammatory, antiasthmatic and antibiosis, meanwhile, they have effects of liver protection, detoxification in the liver, anti-fungus, treatment of acute and chronic hepatitis, liver cirrhosis, anti-free radical and antioxidation. Besides, flavonoids have same effects with phytoestrogen, and can be good applied in fields like medicine and health care products.
Traditional extraction methods of flavonoids include ultrafiltration, enzymolysis approach, adsorption method by coarse pored resin, supercritical fluid extraction, ultrasonic method and microwave extraction method etc. But above traditional methods have problems like low extraction efficiency and high cost, so they can't be scalable to popularize and apply.